U.S. patent number 7,842,395 [Application Number 11/555,678] was granted by the patent office on 2010-11-30 for multiple layer interlayers having a gradient region.
This patent grant is currently assigned to Solutia Inc.. Invention is credited to David Paul Bourcier, John Joseph D'Errico, Aristotelis Karagiannis, Jun Lu, Gary Matis, Andrew Neil Smith, Marcin Wardak.
United States Patent |
7,842,395 |
Lu , et al. |
November 30, 2010 |
Multiple layer interlayers having a gradient region
Abstract
The present invention provides multiple layer interlayers that
can be used in multiple layer glass panel type applications to
reduce the amount of sound transmitted through the panel while also
providing a colored region within a gradient region. The acoustic
effect can be achieved by using two or more polymer sheets having
differing compositions that have been combined into a single
multiple layer interlayer, and the gradient region effect is
achieved by forming a colored region in one or more gradient
regions of the individual layers.
Inventors: |
Lu; Jun (East Longmeadow,
MA), Wardak; Marcin (Agawam, MA), Smith; Andrew Neil
(East Longmeadow, MA), Matis; Gary (Wilbraham, MA),
Karagiannis; Aristotelis (Amherst, MA), D'Errico; John
Joseph (Glastonbury, CT), Bourcier; David Paul (Ludlow,
MA) |
Assignee: |
Solutia Inc. (St. Louis,
MO)
|
Family
ID: |
39217996 |
Appl.
No.: |
11/555,678 |
Filed: |
November 1, 2006 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20080102280 A1 |
May 1, 2008 |
|
Current U.S.
Class: |
428/525;
264/173.16; 428/437; 428/436 |
Current CPC
Class: |
B32B
17/10761 (20130101); B32B 27/30 (20130101); B32B
17/10339 (20130101); Y10T 428/31946 (20150401); Y10T
428/31942 (20150401); Y10T 428/31511 (20150401); Y10T
428/31627 (20150401); Y10T 428/3163 (20150401); Y10T
428/31504 (20150401) |
Current International
Class: |
B32B
27/08 (20060101); B32B 27/22 (20060101); B32B
27/38 (20060101) |
Field of
Search: |
;428/436,437,525
;264/173.16 |
References Cited
[Referenced By]
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Primary Examiner: Nakarani; D. S
Attorney, Agent or Firm: Lewis, Rice & Fingersh,
L.C.
Claims
We claim:
1. A poly(vinyl butyral) interlayer comprising: a single poly(vinyl
butyral) sheet, including: a first plasticized poly(vinyl butyral)
layer having a first gradient region and a first clear region; a
second plasticized poly(vinyl butyral) layer having a second
gradient region and a second clear region; a third plasticized
poly(vinyl butyral) layer having a third gradient region and a
third clear region; wherein the amount of plasticizer in said
second layer is at least 10 parts per hundred greater than the
amount of plasticizer in said first layer, and wherein said first
layer and said second layer each have a residual acetate content of
less than 5 mol percent; wherein the amount of plasticizer in said
second layer is at least 10 parts per hundred greater than the
amount of plasticizer in said third layer, and wherein said third
layer and said second layer each have a residual acetate content of
less than 5 mol percent; wherein at least one of said first
gradient region, said second gradient region and said third
gradient region has a colored region; and, wherein said colored
region has a total alkaline titer that is at least 4 titers less
than the total alkaline titer of the clear region of the layer in
which it is formed.
2. The interlayer of claim 1, wherein said colored region has a
total alkaline titer that is at least 8 titers less than the total
alkaline titer of the clear region of the layer in which it is
formed.
3. The interlayer of claim 1, wherein said colored region
incorporates an epoxy compound.
4. The interlayer of claim 3, wherein said colored region epoxy
compound is an epoxy resin.
5. The interlayer of claim 4, wherein said epoxy resin is selected
from the group consisting of an epoxide or diepoxide of
poly(oxypropylene) glycol.
6. The interlayer of claim 1, wherein said first gradient region,
said second gradient region and said third gradient region have a
ratio of the height of said gradient region, in the layer in which
it is formed, to the height of the clear region below it of greater
than 0.25.
7. The interlayer of claim 6, wherein said first gradient region,
said second gradient region and said third gradient region have
said ratio of the height of said gradient region, in the layer in
which it is formed, to the height of the clear region below it of
greater than 0.4.
8. The interlayer of claim 1, wherein the amount of plasticizer in
said second layer is at least 15 parts per hundred greater than the
amount of plasticizer in said first layer, and wherein the amount
of plasticizer in said second layer is at east 15 parts per hundred
greater than the amount of plasticizer in said third layer.
9. The interlayer of claim 1, wherein said second layer has a
residual hydroxyl content per weight percentage that is at least 2%
lower than the residual hydroxyl content per weight percentage of
said first layer.
10. The interlayer of claim 1, wherein said second layer has a
residual hydroxyl content per weight percentage that is at least 4%
lower than the residual hydroxyl content per weight percentage of
said first polymer layer.
11. The interlayer of claim 1, wherein said second layer has a
residual hydroxyl content per weight percentage that is at least 8%
lower than the residual hydroxyl content per weight percentage of
said first polymer layer.
12. The interlayer of claim 1, wherein said second layer has a
residual hydroxyl content per weight percentage of less than 17.0%
and said first polymer layer has a residual hydroxyl content per
weight percentage of less than 20%.
13. The interlayer of claim 1, wherein said first layer and said
second layer each have a residual acetate content of less than 3
mol percent.
14. The interlayer of claim 1, wherein said first layer and said
second layer each have a residual acetate content of less than 1
mol percent.
15. The interlayer of claim 1, wherein said colored region is said
entire gradient region.
16. The interlayer of claim 1, wherein said colored region is a
subportion of said gradient region.
17. The polymer interlayer of claim 1, wherein said first gradient
region has a colored region.
18. The interlayer of claim 1, wherein said second gradient region
has a colored region.
19. The interlayer of claim 1, wherein said first gradient region
and said second gradient region each have a colored region.
20. The interlayer of claim 1, wherein said third gradient region
has a colored region.
21. The interlayer of claim 1, wherein said third gradient region
and said second gradient region each have a colored region.
22. The interlayer of claim 1, wherein said first, second and third
gradient region each have a colored region.
23. A multiple layer glazing panel comprising a poly(vinyl butyral)
interlayer comprising: a single poly(vinyl butyral) sheet,
including: a first plasticized poly(vinyl butyral) layer having a
first gradient region and a first clear region; a second
plasticized poly(vinyl butyral) layer having a second gradient
region and a second clear region; a third plasticized poly(vinyl
butyral) layer having a third gradient region and a third clear
region; wherein the amount of plasticizer in said second layer is
at least 10 parts per hundred greater than the amount of
plasticizer in said first layer, and wherein said first layer and
said second layer each have a residual acetate content of less than
5 mol percent; wherein the amount of plasticizer in said second
layer is at least 10 parts per hundred greater than the amount of
plasticizer in said third layer, and wherein said third layer and
said second layer each have a residual acetate content of less than
5 mol percent; wherein at least one of said first gradient region,
said second gradient region and said third gradient region
comprises has a colored region; and, wherein said colored region
has a total alkaline titer that is at least 4 titers less than the
total alkaline titer of the clear region of the layer in which it
is formed.
24. A method of making a multiple layer interlayer, comprising:
coextruding a first plasticized poly(vinyl butyral) melt to form a
first layer having a first gradient region and a first clear
region; and a second plasticized polyvinyl butyral) melt to form a
second layer having a second gradient region and a second clear
region; and a third plasticized poly(vinyl butyral) melt to form a
third layer having a third gradient layer and a third clear region;
wherein said second layer is between said first layer and said
third layer; wherein the amount of plasticizer in said second layer
is at least 10 parts per hundred greater than the amount of
plasticizer in said first layer, and wherein said first layer and
said second layer each have a residual acetate content of less than
5 mol percent: wherein the amount of plasticizer in said second
layer is at least 10 parts per hundred greater than the amount of
plasticizer in said third layer, and wherein said third layer and
said second layer each have a residual acetate content of less than
5 mol percent; wherein at least one of said first gradient region,
said second gradient region and said third gradient region has a
colored region; and, wherein said colored region has a total
alkaline titer that is at least 4 titers less than the total
alkaline titer of the clear region of the layer in which it is
formed.
Description
FIELD OF THE INVENTION
The present invention is in the field of polymer interlayers and
glass panels comprising polymer interlayers, and, more
specifically, the present invention is in the field of polymer
interlayers comprising multiple thermoplastic sheets.
BACKGROUND
Poly(vinyl butyral) (PVB) is commonly used in the manufacture of
polymer sheets that can be used as interlayers in
light-transmitting laminates such as safety glass or polymeric
laminates. Safety glass often refers to a transparent laminate
comprising a poly(vinyl butyral) sheet disposed between two sheets
of glass. Safety glass often is used to provide a transparent
barrier in architectural and automotive openings. Its main function
is to absorb energy, such as that caused by a blow from an object,
without allowing penetration through the opening or the dispersion
of shards of glass, thus minimizing damage or injury to the objects
or persons within an enclosed area. Safety glass also can be used
to provide other beneficial effects, such as to attenuate acoustic
noise, reduce UV and/or IR light transmission, and/or enhance the
appearance and aesthetic appeal of window openings.
An important consideration for the formulation of the thermoplastic
interlayer is the sound transmission character of the finished
product. Generally it is desirable to use interlayers that reduce
the level of outside noise that is transmitted through the glass. A
conventional single polymer sheet interlayer that has been modified
to improve sound performance will usually have one or more physical
characteristics modified in order to reduce the percentage
transmission of sound through the glass. Conventional attempts at
such acoustic dampening have included using thermoplastic polymers
with low glass transition temperatures. Single sheet interlayers
that have been formulated to improve sound transmission
characteristics, however, are typically difficult to handle and are
limited in the compositional variations that can be pragmatically
employed.
Recent attempts to improve sound transmission characteristics while
also maintaining manageability of the interlayer have involved
using multiple polymer sheet layers in place of the conventional
single polymer sheet interlayer. For example, two adjacent layers
of thermoplastic polymer have been employed where the layers have
dissimilar characteristics (see, for example U.S. Pat. Nos.
5,340,654 and 5,190,826, and U.S. Patent Application 2003/0139520
A1).
Unfortunately, the advent of multiple layer interlayers has
resulted in the reemergence of challenges that had been overcome
for single layer interlayers. For example, while incorporation of a
colored gradient into a thicker, single polymer sheet interlayer
has been known for some time (see, for example, U.S. Pat. Nos.
4,316,868 and 3,799,718), the incorporation of a colored gradient
into a multiple layer interlayer having two or more thinner polymer
sheets presents processing difficulties that can result in
substandard appearance, stability, and/or glass adhesion in
finished laminated glass products.
Further improved compositions and methods are needed to enhance the
sound dampening characteristics of multiple layer glass panels, and
specifically multiple layer glass panels comprising poly(vinyl
butyral) layers, while allowing facile processing and without
negatively impacting optical qualities.
SUMMARY OF THE INVENTION
The present invention provides multiple layer interlayers that can
be used in multiple layer glass panel type applications to reduce
the amount of sound transmitted through the panel while also
providing a colored region within a gradient region. The acoustic
effect can be achieved by using two or more polymer sheets having
differing compositions that have been combined into a single
multiple layer interlayer, and the gradient region effect is
achieved by forming a colored region in one or more gradient
regions of the individual layers.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 represents a schematic cross sectional view of a multiple
manifold coextrusion device of the present invention.
DETAILED DESCRIPTION
According to the present invention, it has now been surprisingly
discovered that a colored region can be incorporated into a
gradient region of a multiple layer acoustic-type interlayer using,
for example, a multiple manifold coextrusion device.
As used herein, a "gradient region" is the portion of a polymer
sheet that corresponds with the top portion of a windshield in a
finished product in which gradients are conventionally formed.
Gradient regions of the present invention can have any suitable
height that does not obscure a driver's view. A gradient region can
extend to the very top edge of an interlayer or it can be a stripe
that is located at the top of the interlayer that leaves a small
region above the gradient region that is not part of the gradient
region. In various embodiments, a "gradient region" refers to the
top portion of a polymer sheet as it is installed in a finished
vehicle windshield, as viewed from the interior of the vehicle. In
various embodiments, the gradient region of the interlayer
corresponds to the top 8 centimeters to 26 centimeters of the
finished windshield. The gradient region has conventionally been
used to provide a shaded gradient that blocks a portion of the
solar radiation impinging upon that portion of the windshield.
As used herein, each polymer sheet within an interlayer has a
gradient region, although the region may be devoid of coloration,
thereby rendering the gradient region indistinct from the remainder
of the polymer sheet, which is known as the "clear" region.
Interlayers of the present invention include at least one colored
region within a gradient region of a polymer sheet. As used herein,
a "colored region" is a portion of the gradient region that has a
pigment, dye, or other colorant that results in a color or
appearance that is distinct from the remainder of the polymer
sheet. In various embodiments, a pigment is used to impart color to
the colored region.
In various embodiments, a colored region can be formed in a
gradient region so that the color has consistent composition and
optical character throughout the gradient region. In other
embodiments, coloration will change in a uniform or non-uniform
manner to produce a gradient with the desired visual effect. For
example, a gradient could range from clear to opaque in a linear,
exponential, or discrete step change function, with, for example,
optical density values ranging from zero to four within the
gradient region. Patterns and images can also be formed within the
colored region. In further embodiments, a colored region can be
formed in a defined subregion of the gradient region. For example,
a colored region can be formed in a centered subregion of the
gradient region that has the same height as the gradient region but
only half the width, which results in a rectangular subregion of
the gradient region having a coloration. Many other shapes and
distributions of coloration within a subregion are possible and
within the scope of the present invention. Black, white, and gray,
as well as all other colors, are included within the scope of a
colored region.
A colored region can be formed in any suitable manner, and, in a
preferred embodiment, the colored region is formed in a polymer
layer during extrusion using coextrusion or extrusion coating
techniques, for example. In coextruded embodiments, for example, a
polymer melt comprising the polymer resin, plasticizer, added
agents, and the coloring agent are mixed and coextruded with a
conventional polymer melt, resulting in a single polymer sheet
having a gradient region formed therein in which coloring agents
are dispersed through the gradient region.
Colored regions can be formed in gradient regions of one or more
polymer sheets in an interlayer. For interlayers in which more than
one polymer sheet has a colored region, the multiple colored
regions can be colored the same or different. If different patterns
or colors are used, combinative effects can be created that would
be more difficult or impossible to achieve with a colored region in
a single layer. In multiple colored region embodiments, colored
regions can be the same shape and size, or they can be different.
For example, a first colored region can be formed in a first
polymer sheet that occupies the entire gradient region, and a
second colored region can be formed that occupies a subregion of
the gradient region in a second polymer sheet.
The adhesion of multiple layer interlayers to glass is controlled
through the use of adhesion control agents. Adhesion control
agents, for example, can be in the form of sodium salts, potassium
salts, or magnesium salts of carboxylic acids. It is preferred that
the adhesion level in gradient regions having a colored region is
at the same level as the adhesion level in the adjacent clear
region, which is properly controlled to meet impact criteria
described in various government standards (for examples, ANSI
Z26.01 Item 1 and EC R43). Lower adhesion in the gradient region
can potentially cause the glass to de-bound or delaminate from the
interlayer in the event of an impact, resulting in shards of glass
or flying glass, thereby defeating the safety features of laminated
glass.
For the purpose of the present invention, the adhesion of
interlayer to, for example, glass, can be measured by pummel
adhesion, as described below. An adhesion difference, or adhesion
delta, between a clear region and a gradient region is preferably
less than 1 pummel unit.
In various embodiments of the present invention, a gradient region
having a colored region has an adhesion control agent concentration
that is lower than the adhesion control agent concentration in the
remainder of the polymer sheet. In various embodiments, the total
alkaline titer of the gradient region is at least 4 less than the
total alkaline titer of the clear region of the polymer sheet. This
difference can be easily achieved, for example, by altering the
salt concentrations in one or more of the melts used to form the
clear and gradient regions during coextrusion. By altering the
relative concentrations of the adhesion control agents in the
gradient region, the adhesion of the gradient region to, for
example, glass, can be increased.
In various embodiments of the present invention, the adhesion of a
gradient region comprising a colored region is improved through the
incorporation of an epoxy resin in the melt used to form the
gradient region. Any suitable epoxy resin can be used, and, in
preferred embodiments, an epoxy composition is selected from (a)
epoxy resins comprising monomeric diglycidyl ether of bisphenol-A;
(b) epoxy resins comprising monomeric diglycidyl ether of
bisphenol-F; (c) epoxy resins comprising hydrogenated diglycidyl
ether of bisphenol-A; (d) polyepoxidized phenol novolacs; (e)
diepoxides of polyglycols, alternatively known as an epoxy
terminated polyether; (f) glycidyl alkyl ether; and (g) a mixture
of any of the foregoing epoxy resins of (a) through (f). Further
information on these classes is in the Encyclopedia of Polymer
Science and Technology, Volume 6, 1967, Interscience Publishers,
N.Y., pages 209-271. Epoxy resin can be incorporated in
concentrations of 0.5 to 10 parts per hundred relative to the main
resin used (for example, poly(vinyl butyral)) in the colored region
or 1 to 5 parts per hundred relative to the main resin used in the
colored region.
A suitable commercially available diglycidyl ether of bisphenol-A
of class (a) is DER 331 from Dow Chemical Company. A diglycidyl
ether of bisphenol-F epoxy of class (b) is EPON Resin DPL-862 and a
hydrogenated diglycidyl ether of bisphenol-A epoxy of class (c) is
EPONEX Resin 1510, both of the latter available from Shell Chemical
Company. A polyepoxidized phenol formaldehyde novolac of class (d)
is available from Dow Chemical as DEN 431. A diepoxide of
poly(oxypropylene) glycol of class (e) is available from Dow
Chemical as DER 732. A glycidyl alkyl ether of class (f) is
available from Hexion as Heloxy Modifier 116.
In various embodiments of the present invention, the gradient
region is extended to a greater proportion of the interlayer. In
conventional applications, for example, the ratio of the height of
the gradient region to the height of the clear region below it, the
"gradient to clear ratio", is 0.1-0.25. In embodiments of the
present invention in which the gradient region is increased, the
gradient to clear ratio is greater than 0.25, greater than 0.3, or
greater than 0.4. These embodiments are particularly useful to
applications that integrate the windshield and a sunroof with a
single laminated glass panel. In these embodiments, the gradient
region extends from the usual starting point at the top of the
forward viewing area to the sun roof area. Other applications for
this type of gradient region are also within the scope of the
present invention.
Multiple layer interlayers of the present invention are preferably
formed using a multiple manifold coextrusion device such as the one
shown in FIG. 1. As shown in schematic cross sectional view
generally at 10, an extrusion device has a first die manifold 12 a
second die manifold 14, and a third die manifold 16. A probe 18 is
disposed within the first die manifold. The probe 18 has an orifice
that has a width that is approximately the width of the desired
finished colored region.
The device shown in FIG. 1 operates by simultaneously extruding
polymer melts from each manifold (12, 14, 16) toward the extrusion
opening 20, where the multiple layer interlayer is extruded as a
composite of three individual layers. Sheet thickness can be varied
by adjusting the distance between the die lips at the extrusion
opening 20. A probe can also be added to the second manifold 14
and/or the third manifold 16--either in addition to or in place of
the first probe 18--in order to vary the location of one or more
colored regions within the finished interlayer.
In other embodiments, an extrusion device can have 2, 3, or more
die manifolds, each of which can be supplied with a separate
polymer melt. Probes can be inserted into one or more of the
manifolds in order to form colored regions in one or more of the
coextruded melts.
Multiple layer interlayers of the present invention that function
to reduce sound transmission through a glass panel include those
known in the art, for example, and not limited to those disclosed
in U.S. Pat. No. 5,190,826, which teaches the use of acetals of
differing carbon length, Japanese Patent Application 3124441A and
U.S. Patent Application 2003/0139520 A1, which teach the use of
differing polymerization degree, and Japanese Patent 3,377,848 and
U.S. Pat. No. 5,340,654, which teach the use of residual acetate
levels of at least 5 mole % in one of two adjacent sheets as a
compositional difference.
In a preferred embodiment, superior sound suppression
characteristics can be imparted on multiple layer glass panels by
incorporating a multiple layer interlayer into the panels, where
the interlayer comprises two polymer sheets having different
plasticizer concentrations. By formulating polymer sheets to stably
contain differing plasticizer concentrations, as described in
detail herein throughout, it has been found that sound transmission
through multiple layer glass panels can be reduced by, for example,
more than 2 decibels in the frequency or frequency region of
interest. Further, because embodiments having three polymer sheet
layers can be formulated to be easily handled and used as a direct
replacement for conventional interlayers in conventional processes,
interlayers of the present invention will be usable in many
applications without requiring any modification to the
manufacturing method used in the applications. For example,
automotive windshield applications can involve the use of a
conventional polymeric interlayer that can be replaced with an
interlayer of the present invention without altering the lamination
process used to form the finished windshield.
As used herein, an "interlayer" is any thermoplastic construct that
can be used in multiple layer glass applications, such as safety
glass in windshields and architectural windows, and a "multiple
layer" interlayer is any interlayer that is formed by combining,
through laminating processes or through coextrusion processes, two
or more individual layers into a single interlayer.
In various embodiments of the present invention, a multiple layer
interlayer comprises two polymer sheets disposed in contact with
each other, wherein each polymer sheet comprises a thermoplastic
polymer, as detailed elsewhere herein, and wherein at least one of
the polymer sheets has a gradient region having a colored region.
The thermoplastic polymer can be the same or different in each
sheet. In these embodiments, a sound dampening effect is imparted
to the interlayer by fabricating each polymer sheet with a
different plasticizer content, and then laminating the two layers
together to form a single, multiple layer interlayer. The
composition of the polymer sheets is such that net migration of
plasticizer from one polymer sheet to another is negligible or
zero, thereby maintaining the plasticizer differential.
In various embodiments of the present invention, the colored region
in the gradient region of the multiple layer interlayer can be
stably formulated to have the same plasticizer concentration as the
plasticizer concentration in one of the polymer sheets in a
multiple layer interlayer, including the clear region in the
polymer sheet in which the colored region is formed.
In various embodiments of the present invention, the colored region
in the gradient region of the multiple layer interlayer can be
stably formulated to have a plasticizer concentration that is
different from any of the plasticizer concentrations of the polymer
sheets of a multiple layer interlayer, including the clear region
in the polymer sheet in which the colored region is formed.
In various embodiments of the present invention, a polymer sheet
can be stably formulated to have the same plasticizer concentration
in each sheet, while the colored region in a gradient region of the
multiple layer interlayer is stably formulated to have a
plasticizer concentration that is different from the plasticizer
concentrations of the polymer sheets, including the clear region in
the polymer sheet in which the colored region is formed.
As used herein, "plasticizer content" can be measured as parts per
hundred resin (phr) parts, on a weight per weight basis. For
example, if 30 grams of plasticizer is added to 100 grams of
polymer resin, then the plasticizer content of the resulting
plasticized polymer would be 30 phr. As used herein throughout,
when the plasticizer content of a polymer sheet is given, the
plasticizer content of that particular sheet is determined with
reference to the phr of the plasticizer in the melt that was used
to produce that particular sheet.
For sheets of unknown plasticizer content, the plasticizer content
can be determined via a wet chemical method in which an appropriate
solvent, or a mixture of solvents, is used to extract the
plasticizer out of the sheet. By knowing the weight of the sample
sheet and the weight of the extracted sheet, the plasticizer
content in phr can be calculated. In the case of a two polymer
sheet interlayer, one polymer sheet can be physically separated
from another before the plasticizer content in each of the polymer
sheets is measured.
In various embodiments of the present invention, the plasticizer
content of the two polymer sheets differ by at least 8 phr, 10 phr,
12 phr, 15 phr, 18 phr, 20 phr, or 25 phr. Each sheet can have, for
example 30 to 100 phr, 40 to 90 phr, or 50 to 80 phr.
In various embodiments of the present invention, the residual
hydroxyl contents of the thermoplastic polymer components of the
polymer sheets are different, which allows for the fabrication of
sheets with stable plasticizer differences. As used herein,
residual hydroxyl content (as vinyl hydroxyl content or poly(vinyl
alcohol) (PVOH) content) refers to the amount of hydroxyl groups
remaining as side groups on the polymer chains after processing is
complete. For example, poly(vinyl butyral) can be manufactured by
hydrolyzing poly(vinyl acetate) to poly(vinyl alcohol), and then
reacting the poly(vinyl alcohol) with butyraldehyde to form
poly(vinyl butyral). In the process of hydrolyzing the poly(vinyl
acetate), typically not all of the acetate side groups are
converted to hydroxyl groups. Further, reaction with butyraldehyde
typically will not result in all hydroxyl groups being converted to
acetal groups. Consequently, in any finished poly(vinyl butyral),
there will typically be residual acetate groups (as vinyl acetate
groups) and residual hydroxyl groups (as vinyl hydroxyl groups) as
side groups on the polymer chain. As used herein, residual hydroxyl
content is measured on a weight percent basis per ASTM 1396.
In various embodiments of the present invention, the residual
hydroxyl content of the two adjacent polymer sheets can differ by
at least 1.8%, 2.0%, 2.2%, 2.5%, 3.0%, 4.0%, 5.0%, 7.5%, or by at
least 10%. This difference is calculated by subtracting the
residual hydroxyl content of the sheet with the lower residual
hydroxyl content from the residual hydroxyl content of the sheet
with the greater residual hydroxyl content. For example, if a first
polymer sheet has a residual hydroxyl content of 20 weight percent,
and a second polymer sheet has a residual hydroxyl content of 17
weight percent, then the residual hydroxyl content of the two
sheets differs by 3 weight percent.
For a given type of plasticizer, the compatibility of that
plasticizer in a poly(vinyl butyral) is largely determined by the
hydroxyl content. Typically, poly(vinyl butyral) with a greater
residual hydroxyl content will result in a reduced plasticizer
compatibility or capacity. Likewise, poly(vinyl butyral) with a
lower residual hydroxyl content will result in an increased
plasticizer compatibility or capacity. These properties can be used
to select the hydroxyl content of each poly(vinyl butyral) polymer
and formulate each of the polymer sheets to allow for the proper
plasticizer loading and to stably maintain the difference in
plasticizer content between the polymer sheets.
As is known in the art, residual hydroxyl content can be controlled
by controlling reaction times, reactant concentrations, and other
variables in the manufacturing process. In various embodiments, the
residual hydroxyl content of the two sheets is as follows: first
sheet less than 25% and second sheet less than 23%; first sheet
less than 23% and second sheet less than 21%; first sheet less than
21% and second sheet less than 19%; first sheet less than 20% and
second sheet less than 17%; first sheet less than 18% and second
sheet less than 15%; first sheet less than 15% and second sheet
less than 12%. In any of these embodiments, any of the values given
in the previous paragraph for the difference in hydroxyl content
between the two layers can be used.
As used herein, tensile break stress, or tensile strength, of a
polymer sheet is defined and measured according to the method
described in JIS K6771. In various embodiments of the present
invention, the two polymer sheets have a tensile break stress
according to the following, wherein the first polymer sheet in the
following list is the polymer sheet with the lower plasticizer
content: first polymer sheet greater than 135 kilograms per square
centimeter and second polymer sheet less than 120 kilograms per
square centimeter; first polymer sheet greater than 150 kilograms
per square centimeter and second polymer sheet less than 135
kilograms per square centimeter; first polymer sheet greater than
165 kilograms per square centimeter and second polymer sheet less
than 150 kilograms per square centimeter; or first polymer sheet
greater than 180 kilograms per square centimeter and second polymer
sheet less than 165 kilograms per square centimeter; or in general
the two polymer sheets differ in tensile break stress by at least
15 kilograms per square centimeter.
For the purposes of the present invention, the difference in sound
transmission loss between a first polymer sheet formed from
composition (A) and a second polymer sheet formed from composition
(B) in a multiple layer interlayer is determined according to the
following:
First, form a first polymer sheet (Sheet A) having a thickness of
0.7620 millimeters (30 mils) and composed of (A) and a second
polymer sheet (Sheet B) having a thickness of 0.7620 millimeters
(30 mils) and composed of (B).
Determine which sheet--Sheet A or Sheet B--has the higher tensile
modulus (see procedure elsewhere herein).
Laminate a 47 centimeter.times.74 centimeter rectangle of Sheet A
between two layers of 2.1 millimeter thick float glass to form
Panel A.
Laminate 47 centimeter.times.74 centimeter rectangle of Sheet B
between two layers of 2.1 millimeter thick float glass to form
Panel B.
Determine the coincident frequency of the Panel having the Sheet
with the higher tensile modulus (see elsewhere herein for
procedure), which are designated the "reference panel" and the
"reference interlayer."
Measure the Sound Transmission Loss (STL) of Panel A and Panel B at
the coincident frequency determined in the last step with ASTM E90
(95) at a fixed temperature of 20.degree. C.
The difference in sound transmission loss between two sheets in a
multiple layer interlayer is then computed to be: |(STL Panel
A)-(STL Panel B)|
For purposes of the present invention a "coincident frequency"
means the frequency at which a panel exhibits a dip in sound
transmission loss due to "coincident effect", which can be
experimentally determined from the plot of sound transmission loss
versus 1/3 octave band frequency. In the various embodiments of the
present invention, the coincident frequency of a panel is typically
in the range of 2,000 to 6,000 Hertz, and can also be estimated
from a monolithic sheet of glass having a thickness equal to the
combined glass thickness of glass in the reference panel from the
algorithm
.times..times. ##EQU00001##
where "d" is the total glass thickness in millimeters and "f.sub.c"
is in Hertz.
As used herein, the coincident frequency of the reference panel is
also referred to as the "reference frequency".
In typical laminates with two outer layers of glass, the "combined
glass thickness" is the sum of the thickness of the two layers of
glass. In more complex laminates with three or more layers of
glass, the combined glass thickness would be the sum of the three
or more layers of glass.
In various embodiments of the present invention, multiple layer
interlayers of the present invention comprise at least two polymer
sheets exhibiting a difference in sound transmission loss, the
determination of which is described elsewhere herein, of at least 2
decibels, more preferably 4 decibels, and even more preferably 6
decibels or higher or 8 decibels or higher.
In various embodiments of the present invention, two adjacent
polymer sheets of the present invention have the differing
plasticizer content as described above, and each further has a
residual acetate content of less than 5 mole %, less than 4 mole %,
less than 3 mole %, less than 2 mole %, or less than 1 mole %.
These residual acetate concentrations can be combined with the
residual hydroxyl contents given above, in any combination, to form
two polymer sheets of the present invention having the described
differences in plasticizer content and residual hydroxyl content
while having little to no residual acetate content. Further
embodiments of multiple layer interlayers of the present invention
include interlayers having more than two polymer sheets, wherein
one or more of the additional polymer sheets has a residual acetate
content of less than 5 mole %, less than 4 mole %, less than 3 mole
%, less than 2 mole %, or less than 1 mole %.
Further embodiments of the present invention include any of the
foregoing embodiments further comprising a third polymer sheet.
Addition of this third polymer sheet layer results in a three layer
construct that has the following structure for interlayers with a
plasticizer differential between adjacent polymer sheets: First
polymer sheet with relatively low plasticizer content//Second
polymer sheet with relatively high plasticizer content//Third
polymer sheet. This third polymer sheet can have the same
composition as the first polymer sheet, or it can be different.
In various embodiments, the third polymer sheet has the same
composition as the first polymer sheet, which provides a three
layer laminated interlayer that has a relatively difficult to
handle polymer sheet laminated between two relatively easy to
handle sheets, resulting in a multiple layer interlayer that is
relatively easy to handle and which can be incorporated directly
into existing processes that previously used a single polymer sheet
having the composition of the outer two polymer sheets of the
interlayer of the present invention, or a composition that results
in similar processing characteristics (for example, blocking
tendency).
In other embodiments utilizing three polymer sheets in a single
interlayer, the third polymer sheet has a different composition
than the first polymer sheet, and the differences in composition
between the third polymer sheet and the second polymer sheet can be
any of the differences given above for the differences between the
first polymer sheet and the second polymer sheet.
For example, one exemplary embodiment would be: first polymer sheet
with a residual hydroxyl content of 20%//second polymer sheet with
a residual hydroxyl content of 16%//third polymer sheet with a
residual hydroxyl content of 18%. It will be noted that, in this
example, the third polymer sheet differs from the second polymer
sheet at least in that it has a residual hydroxyl content that is
2% greater than the hydroxyl content of the second polymer sheet.
Of course, any of the other differences noted herein throughout can
singly or in combination distinguish the third polymer layer from
the second polymer layer.
In three layer embodiments described herein, at least one of the
polymer sheets has a colored region in a gradient region.
In addition to the three layer embodiments described herein,
further embodiments include interlayers having more than three
layers in which further low residual hydroxyl sheets can be used,
for example, iterations of polymer sheets having alternating
plasticizer contents with alternating hydroxyl content and
optionally low or negligible residual acetate content. Interlayers
formed in such a manner can have, for example, 4, 5, 6, or up to 10
individual layers.
Other conventional layers, as are known in the art, can be
incorporated into the interlayers of the present invention. For
example, polymer films (described in detail elsewhere herein) such
as polyesters like poly(ethylene terephthalate) having a metallized
layer, an infrared reflecting stack, or other performance layer
deposited thereon, can be included between any two layers of
polymer sheets of the present invention. For example, in a two
layer embodiment, an interlayer can be fabricated with the
following layout: polymer sheet with relatively high plasticizer
content//polyester film having a performance layer//polymer sheet
with relatively low plasticizer content. In general, additional
layers of thermoplastics, such as poly(vinyl butyral), polyester
films, primer layers, and hardcoat layers can be added to the
multiple layer interlayers of the present invention according to
the desired result and the particular application.
For each interlayer embodiment of the present invention in which
two or more separate polymer sheets are disposed in contact with
one another and subsequently laminated into a single interlayer,
there also exists an embodiment where a coextruded interlayer is
formed to have the same layer arrangement, which, for the purposes
of the present invention, is considered to be formed of multiple
polymer sheets and is considered a "multiple layer" interlayer.
In addition to the interlayers provided herein, the present
invention also provides methods of reducing the level of sound
through an opening, comprising the step of disposing in the opening
a multiple layer glass panel comprising any of the interlayers of
the present invention.
The present invention also includes methods of manufacturing an
interlayer, comprising the steps of forming a first polymer sheet
and a second polymer sheet, wherein the two polymer sheets have
different compositions, as described elsewhere herein, and
laminating the two polymer sheets together to form the
interlayer.
The present invention also includes methods of manufacturing an
interlayer, comprising the steps of forming a first polymer sheet,
a second polymer sheet, and a third polymer sheet, wherein the
three polymer sheets have compositions according to the three layer
embodiments as described elsewhere herein, and laminating the three
polymer sheets together to form the interlayer.
The present invention also includes methods of manufacturing a
multiple layer glazing, comprising laminating any of the
interlayers of the present invention between two rigid, transparent
panels, as are known in the art, such as glass or acrylic
layers.
The present invention also includes multiple layer glass panels,
such as windshields and architectural windows, comprising a
multiple layer interlayer of the present invention.
Also included are multiple layer glazing panels having plastics,
such as acrylics, or other suitable materials in place of the glass
panels.
In various embodiments of the present invention, an interlayer
comprises a colored region within the gradient region of one or
more layers of the interlayer.
Polymer Film
As used herein, a "polymer film" means a relatively thin and rigid
polymer layer that functions as a performance enhancing layer.
Polymer films differ from polymer sheets, as used herein, in that
polymer films do not themselves provide the necessary penetration
resistance and glass retention properties to a multiple layer
glazing structure, but rather provide performance improvements,
such as infrared absorption character. Poly(ethylene terephthalate)
is most commonly used as a polymer film.
In various embodiments, the polymer film layer has a thickness of
0.013 mm to 0.20 mm, preferably 0.025 mm to 0.1 mm, or 0.04 to 0.06
mm. The polymer film layer can optionally be surface treated or
coated to improve one or more properties, such as adhesion or
infrared radiation reflection. These functional performance layers
include, for example, a multi-layer stack for reflecting infra-red
solar radiation and transmitting visible light when exposed to
sunlight. This multi-layer stack is known in the art (see, for
example, WO 88/01230 and U.S. Pat. No. 4,799,745) and can comprise,
for example, one or more Angstroms-thick metal layers and one or
more (for example two) sequentially deposited, optically
cooperating dielectric layers. As is also known, (see, for example,
U.S. Pat. Nos. 4,017,661 and 4,786,783), the metal layer(s) may
optionally be electrically resistance heated for defrosting or
defogging of any associated glass layers.
An additional type of polymer film that can be used with the
present invention, which is described in U.S. Pat. No. 6,797,396,
comprises a multitude of nonmetallic layers that function to
reflect infrared radiation without creating interference that can
be caused by metallic layers.
The polymer film layer, in some embodiments, is optically
transparent (i.e. objects adjacent one side of the layer can be
comfortably seen by the eye of a particular observer looking
through the layer from the other side), and usually has a greater,
in some embodiments significantly greater, tensile modulus
regardless of composition than that of any adjacent polymer sheet.
In various embodiments, the polymer film layer comprises a
thermoplastic material. Among thermoplastic materials having
suitable properties are nylons, polyurethanes, acrylics,
polycarbonates, polyolefins such as polypropylene, cellulose
acetates and triacetates, vinyl chloride polymers and copolymers
and the like. In various embodiments, the polymer film layer
comprises materials such as re-stretched thermoplastic films having
the noted properties, which include polyesters, for example
poly(ethylene terephthalate) and poly(ethylene terephthalate)
glycol (PETG). In various embodiments, poly(ethylene terephthalate)
is used, and, in various embodiments, the poly(ethylene
terephthalate) has been biaxially stretched to improve strength,
and has been heat stabilized to provide low shrinkage
characteristics when subjected to elevated temperatures (e.g. less
than 2% shrinkage in both directions after 30 minutes at
150.degree. C.).
Various coating and surface treatment techniques for poly(ethylene
terephthalate) film that can be used with the present invention are
disclosed in published European Application No. 0157030. Polymer
films of the present invention can also include a hardcoat and/or
and antifog layer, as are known in the art.
Polymer Sheet
As used herein, a "polymer sheet" means any thermoplastic polymer
composition formed by any suitable method into a thin layer that is
suitable alone, or in stacks of more than one layer, for use as an
interlayer that provides adequate penetration resistance and glass
retention properties to laminated glazing panels. Plasticized
poly(vinyl butyral) is most commonly used to form polymer
sheets.
The polymer sheet can comprise any suitable polymer, and, in a
preferred embodiment, the polymer sheet comprises poly(vinyl
butyral). In any of the embodiments of the present invention given
herein that comprise poly(vinyl butyral) as the polymeric component
of the polymer sheet, another embodiment is included in which the
polymer component consists of or consists essentially of poly(vinyl
butyral). In these embodiments, any of the variations in additives
disclosed herein can be used with the polymer sheet having a
polymer consisting of or consisting essentially of poly(vinyl
butyral).
In one embodiment, the polymer sheet comprises a polymer based on
partially acetalized poly(vinyl alcohol)s. In another embodiment,
the polymer sheet comprises a polymer selected from the group
consisting of poly(vinyl butyral), polyurethane, polyvinyl
chloride, poly(ethylene vinyl acetate), combinations thereof, and
the like. In other embodiments, the polymer sheet comprises
plasticized poly(vinyl butyral). In further embodiments the polymer
sheet comprises poly(vinyl butyral) and one or more other polymers.
Other polymers having a proper plasticizing capacity can also be
used. In any of the sections herein in which preferred ranges,
values, and/or methods are given specifically for poly(vinyl
butyral) (for example, and without limitation, for plasticizers,
component percentages, thicknesses, and characteristic-enhancing
additives), those ranges also apply, where applicable, to the other
polymers and polymer blends disclosed herein as useful as
components in polymer sheets.
For embodiments comprising poly(vinyl butyral), the poly(vinyl
butyral) can be produced by known acetalization processes that
involve reacting poly(vinyl alcohol) with butyraldehyde in the
presence of an acid catalyst, followed by neutralization of the
catalyst, separation, stabilization, and drying of the resin, with
the understanding that in various embodiments, residual hydroxyl
content will be controlled, as described elsewhere herein.
In various embodiments, the polymer sheet comprises poly(vinyl
butyral) having a molecular weight greater than 30,000, 40,000,
50,000, 55,000, 60,000, 65,000, 70,000, 120,000, 250,000, or
350,000 grams per mole (g/mole or Daltons). Small quantities of a
dialdehyde or trialdehyde can also be added during the
acetalization step to increase molecular weight to greater than 350
Daltons (see, for example, U.S. Pat. Nos. 4,874,814; 4,814,529; and
4,654,179). As used herein, the term "molecular weight" means the
weight average molecular weight.
If additional, conventional polymer sheets are used in addition to
any of the embodiments described above as having plasticizer
content differences, those additional, conventional polymer sheets
can comprise 20 to 60, 25 to 60, 20 to 80, or 10 to 70 parts
plasticizer per one hundred parts of resin (phr). Of course other
quantities can be used as is appropriate for the particular
application. In some embodiments, the plasticizer has a hydrocarbon
segment of fewer than 20, fewer than 15, fewer than 12, or fewer
than 10 carbon atoms.
Any suitable plasticizers can be added to the polymer resins of the
present invention in order to form the polymer sheets. Plasticizers
used in the polymer sheets of the present invention can include
esters of a polybasic acid or a polyhydric alcohol, among others.
Suitable plasticizers include, for example, triethylene glycol
di-(2-ethylbutyrate), triethylene glycol di-(2-ethylhexanoate),
triethylene glycol diheptanoate, tetraethylene glycol diheptanoate,
dihexyl adipate, dioctyl adipate, hexyl cyclohexyladipate, mixtures
of heptyl and nonyl adipates, diisononyl adipate, heptylnonyl
adipate, dibutyl sebacate, polymeric plasticizers such as the
oil-modified sebacic alkyds, and mixtures of phosphates and
adipates such as disclosed in U.S. Pat. No. 3,841,890 and adipates
such as disclosed in U.S. Pat. No. 4,144,217, and mixtures and
combinations of the foregoing. Other plasticizers that can be used
are mixed adipates made from C.sub.4 to C.sub.9 alkyl alcohols and
cyclo C.sub.4 to C.sub.10 alcohols, as disclosed in U.S. Pat. No.
5,013,779, and C.sub.6 to C.sub.8 adipate esters, such as hexyl
adipate. In preferred embodiments, the plasticizer is triethylene
glycol di-(2-ethylhexanoate).
Adhesion control agents (ACAs) can also be included in the polymer
sheets of the present invention to impart the desired adhesiveness.
These agents can be incorporated into the outer sheets in a three
polymer sheet embodiment, for example. Any of the ACAs disclosed in
U.S. Pat. No. 5,728,472 can be used. Additionally, residual sodium
acetate and/or potassium acetate can be adjusted by varying the
amount of the associated hydroxide used in acid neutralization. In
various embodiments, polymer sheets of the present invention
comprise, in addition to sodium acetate, magnesium bis(2-ethyl
butyrate)(chemical abstracts number 79992-76-0). The magnesium salt
can be included in an amount effective to control adhesion of the
polymer sheet to glass.
Additives may be incorporated into the polymer sheet to enhance its
performance in a final product. Such additives include, but are not
limited to, plasticizers, dyes, pigments, stabilizers (e.g.,
ultraviolet stabilizers), antioxidants, flame retardants, other IR
absorbers, anti-block agents, combinations of the foregoing
additives, and the like, as are known in the art.
Agents that selectively absorb light in the visible or near
infrared spectrum can be added to any of the appropriate polymer
sheets. Agents that can be used include dyes and pigments such as
indium tin oxide, antimony tin oxide, or lanthanum hexaboride
(LaB.sub.6).
Any suitable method can be used to produce the polymer sheets and
the multiple layer interlayers of the present invention. Details of
suitable processes for making poly(vinyl butyral) are known to
those skilled in the art (see, for example, U.S. Pat. Nos.
2,282,057 and 2,282,026). In one embodiment, the solvent method
described in Vinyl Acetal Polymers, in Encyclopedia of Polymer
Science & Technology, 3.sup.rd edition, Volume 8, pages
381-399, by B. E. Wade (2003) can be used. In another embodiment,
the aqueous method described therein can be used. Poly(vinyl
butyral) is commercially available in various forms from, for
example, Solutia Inc., St. Louis, Mo. as Butvar.TM. resin.
As used herein, "resin" refers to the polymeric (for example
poly(vinyl butyral)) component that is removed from the mixture
that results from the acid catalysis and subsequent neutralization
of the polymeric precursors. Resin will generally have other
components in addition to the polymer, for example poly(vinyl
butyral), such as acetates, salts, and alcohols. As used herein,
"melt" refers to a mixture of resin with a plasticizer and,
optionally, other additives.
One exemplary method of forming a poly(vinyl butyral) layer
comprises extruding molten poly(vinyl butyral) comprising resin,
plasticizer, and additives and then forcing the melt through a
sheet die (for example, a die having an opening that is
substantially greater in one dimension than in a perpendicular
dimension). Another exemplary method of forming a poly(vinyl
butyral) layer comprises casting a melt from a die onto a roller,
solidifying the resin, and subsequently removing the solidified
resin as a sheet. In either embodiment, the surface texture at
either or both sides of the layer may be controlled by adjusting
the surfaces of the die opening or by providing texture at the
roller surface. Other techniques for controlling the layer texture
include varying parameters of the materials (for example, the water
content of the resin and/or the plasticizer, the melt temperature,
molecular weight distribution of the poly(vinyl butyral), or
combinations of the foregoing parameters). Furthermore, the layer
can be configured to include spaced projections that define a
temporary surface irregularity to facilitate the de-airing of the
layer during lamination processes after which the elevated
temperatures and pressures of the laminating process cause the
projections to melt into the layer, thereby resulting in a smooth
finish.
Fabrication of a multiple layer interlayer can be accomplished by
using known techniques in the art, such as independently producing
three layers of polymer sheet, and then laminating the three sheets
together under appropriate conditions, such as pressure and heat,
to yield a single, multiple layer interlayer.
In various embodiments, the interlayers of the present invention
can have total thicknesses of 0.1 to 2.5 millimeters, 0.2 to 2.0
millimeters, 0.25 to 1.75 millimeters, and 0.3 to 1.5 millimeters
(mm). The individual polymer sheets of a multiple layer interlayer
can have, for example, approximately equal thicknesses that, when
added together, result in the total thickness ranges given above.
Of course, in other embodiments, the thicknesses of the layers can
be different, and can still add to the total thicknesses given
above.
The parameters for the polymer sheet described above apply as well
to any layer in a multiple layer construct of the present invention
that is a poly(vinyl butyral) type layer.
The following paragraphs describe various techniques that can be
used to improve and/or measure the characteristics of the polymer
sheet.
The clarity of a polymer sheet, and particularly a poly(vinyl
butyral) layer, can be determined by measuring the haze value,
which is a quantification of the amount of light scattered away
from the direction of the incident beam in passing through the
layer. The percent haze can be measured according to the following
technique. An apparatus for measuring the amount of haze, a
Hazemeter, Model D25, which is available from Hunter Associates
(Reston, Va.), can be used in accordance with ASTM D1003-61
(Re-approved 1977)-Procedure A, using Illuminant C, at an observer
angle of 2 degrees. In various embodiments of the present
invention, percent haze is less than 5%, less than 3%, and less
than 1%.
The visible transmittance can be quantified using a UV-Vis-NIR
spectrophotometer such as the Lambda 900 made by Perkin Elmer Corp.
by methods described in international standard ISO 9050:1990. In
various embodiments, the transmittance through a polymer sheet of
the present invention is at least 60%, at least 70%, or at least
80%.
Pummel adhesion can be measured according to the following
technique, and where "pummel" is referred to herein to quantify
adhesion of a polymer sheet to glass, the following technique is
used to determine pummel. Two-ply glass laminate samples are
prepared with standard autoclave lamination conditions. The
laminates are cooled to about -18.degree. C. (0.degree. F.) and
manually pummeled with a hammer to break the glass. All broken
glass that is not adhered to the poly(vinyl butyral) layer is then
removed, and the amount of glass left adhered to the poly(vinyl
butyral) layer is visually compared with a set of standards. The
standards correspond to a scale in which varying degrees of glass
remain adhered to the poly(vinyl butyral) layer. In particular, at
a pummel standard of zero, no glass is left adhered to the
poly(vinyl butyral) layer. At a pummel standard of 10, 100% of the
glass remains adhered to the poly(vinyl butyral) layer. Poly(vinyl
butyral) layers of the present invention can have, for example, a
pummel value of between 3 and 10.
Tensile break stress can be determined for a polymer sheet
according to the procedure described in JIS K6771.
As used herein, "titer" can be determined for sodium acetate and
potassium acetate (as used herein, the "total alkaline titer") and
magnesium salts in a sheet sample using the following method.
In order to determine the amount of resin in each sheet sample that
is weighed, the following equation is used, where PHR is defined as
the pounds per hundred pounds of resin including plasticizer and
any other additives to the resin in the original sheet sample
preparation.
.times..times..times..times..times..times..times..times..times..times..ti-
mes..times..times..times. ##EQU00002##
Approximately 5 g of resin in the sheet sample is the target mass
used to estimate the amount of sheet sample to start with, with the
calculated mass of resin in the sheet sample used for each titer
determination. All titrations should be completed in the same
day.
The sheet sample is dissolved into 250 milliliters of methanol in a
beaker. It may take up to 8 hours for the sheet sample to be
completely dissolved. A blank with just methanol is also prepared
in a beaker. The sample and blank are each titrated with 0.00500
normal HCl using an automated pH titrator programmed to stop at a
pH of 2.5. The amount of HCl added to each the sample and the blank
to obtain a pH of 4.2 is recorded. The HCl titer is determined
according to the following:
.times..times..times..times..times..times..times..times..times..times..ti-
mes..times..times..times..times..times..times..times..times..times..times.-
.times..times..times..times..times..times..times..times..times..times..tim-
es..times. ##EQU00003##
To determine magnesium salt titer, the following procedure is
used:
12 to 15 mls of pH 10.00 Buffer solution, prepared from 54 grams of
ammonium chloride and 350 mls of ammonium hydroxide diluted to one
liter with methanol, and 12 to 15 mls of Erichrome Black T
indicator are added to the blank and each sheet sample, all of
which have already been titrated with HCl, as described above. The
titrant is then changed to a 0.000298 g/ml EDTA solution prepared
from 0.3263 g tetrasodium ethylenediaminetetraacetate dihydrate, 5
ml water, diluted to one liter with methanol. The EDTA titration is
measured by light transmittance at 596 nm. The % transmittance is
first adjusted to 100% in the sample or blank before the titration
is started while the solution is a bright magenta-pink color. When
transmittance at 596 nm becomes constant, the EDTA titration is
complete, and the solution will be a deep indigo color. The volume
of EDTA titrated to achieve the indigo blue end point is recorded
for the blank and each sheet sample. Magnesium salt titer is
determined according to the following:
.times..times..times. .times.
.times..times..times..times..times..times..times..times..times..times..ti-
mes..times..times..times..times..times..times..times..times..times..times.-
.times..times..times..times..times..times..times..times..times..times..tim-
es..times..times..times..times..times..times..times..times..times..times..-
times..times..times..times..times..times..times..times..times..times..time-
s..times..times..times..times..times..times. ##EQU00004##
From this result, total alkaline titer, as 1.times.10.sup.-7 mole
of acetate salt per gram resin, can be calculated according to the
following: Total Alkaline Titer=HCl Titer of sheet-(2.times.Total
Magnesium Salt Titer)
The portion of the total alkalinity titer attributable to either
sodium acetate or potassium acetate can be determined by first
determining the total alkaline titer, as described above. After
determining total alkaline titer, destructive analysis on the
polymer sheet can be performed by Inductively Coupled Plasma
Emission Spectroscopy (ICP) resulting in a ppm concentration for
potassium and a ppm concentration for sodium.
The alkaline titer attributable to sodium acetate is defined herein
as the total alkaline titer multiplied by the ratio [ppm
sodium/(ppm sodium+ppm potassium)].
The alkaline titer attributable to potassium acetate is defined
herein as the total alkaline titer multiplied by the ratio [ppm
potassium/(ppm sodium+ppm potassium)].
EXAMPLES
Poly(vinyl butyral) sheets having noted residual hydroxyl content
formulated with various amount of 3GEH (triethylene glycol
di-(2-ethylhexanoate)), and their sheet thicknesses are listed in
Table 1. These sheets are either used to construct the interlayers
of the present invention or used as the reference interlayer for
making reference panels. In all sheets, the residual acetate
contents are negligible and are less than 1 mole %.
TABLE-US-00001 TABLE 1 Residual Tensile PVB Poly(vinyl hydroxyl
Sheet Gradient break Sheet butyral) content 3GEH content thickness
Colored to clear stress, No. sheet (%) (phr) (mil) region ratio
kg/cm.sup.2 1 PVB-1 18.5 38 30 Blue 0.20 230 2 PVB-2 18.5 38 30
Green 0.25 230 3 PVB-3 18.5 38 13 Blue 0.40 230 4 PVB-4 15.9 52 40
Blue 0.24 140 5 PVB-5 16.0 49 45 Blue 0.26 160 6 PVB-6 18.5 38 30
No 0 230 7 PVB-7 15.9 52 30 No 0 140 8 PVB-8 11.2 75 6 No 0 <110
9 PVB-9 10.7 75 6 No 0 <110
Conventional interlayers and examples of the interlayers of the
present invention are shown in the Table 2, where a single asterisk
indicates that the interlayers are stored at either cold
temperature, typically 10.degree. C., or at room temperature,
typically 20 to 23.degree. C. and a double asterisk indicates that
the sheet is a reference sheet.
TABLE-US-00002 TABLE 2 Difference Measured in difference OH 3GEH
content as Measured 3GEH in 3GEH Interlayer construction content
formulated in content in each sheet content with multiple sheets
between multiple sheet after 4 weeks (phr)* between Interlayer
Sheet Sheet sheets 1 Sheet Sheet sheets 1 No. 1** Sheet 2 3*** and
2 (%) 1 Sheet 2 Sheet 3 1 Sheet 2 Sheet 3 and 2 (phr)* 1 PVB 1 --
-- -- 38 -- -- 38 -- -- -- (conventional) 2 PVB 2 -- -- -- 38 -- --
38 -- -- -- (conventional) 3 PVB 1 -- PVB 6 0 38 -- 38 38 -- 38 0
(conventional) 4 PVB 1 -- PVB 2 0 38 -- 38 38 -- 38 0 (conventional
5 PVB 1 PVB 6 PVB 1 0 38 38 38 38 38 38 0 (conventional) 6 PVB 1
PVB 7 -- 2.6 38 52 -- 37.8 52.2 37.8 14.4 7 PVB 3 PVB 8 PVB 3 7.3
38 75 38 37.9 75.7 37.9 37.8 7 PVB 3 PVB 9 PVB 3 7.8 36 75 36 35.9
75.4 35.9 39.5 8 PVB 6 PVB 4 -- 2.6 38 52 -- 37.8 52.2 -- 14.4 9
PVB 6 PVB 5 -- 2.5 38 49 38 38 52 38 14 9 PVB 3 PVB PVB 3 6.7 35
72.9 35 35.0 73.0 35.0 36.0 11
Conventional laminated glass (reference panels), and examples of
laminated glass consisting of interlayers with improvements in
acoustical performance relative to the reference panels are shown
in Table 3. Sheet 1 and Sheet 3 are the reference sheets. STL of
these sheets listed in Table 3 are obtained when they are used as
reference interlayers in accordance with typical laminated glass
construction. In Table 3, a single asterisk designates glass
laminates containing two panes of symmetric glass sheet (each of
the glass sheets has equal thickness), and "STL" refers to Sound
Transmission Loss.
TABLE-US-00003 TABLE 3 STL difference Combined STL at reference
between sheet 1 and Laminate Intelayer contruction glass thickness
frequency (dB) sheet 2 at reference No. Sheet 1 Sheet 2 Sheet 3
(mm)* sheet 1 sheet 2 sheet 3 frequency (dB) 1 PVB 1 -- -- 4.2 31
-- 0 2 PVB 2 -- -- 4.2 31 -- 0 3 PVB 1 -- PVB 6 4.2 31 -- 31 0 4
PVB 1 -- PVB 2 4.2 32 -- 32 0 5 PVB 1 PVB 6 PVB 1 4.2 32 32 32 0 6
PVB 1 PVB 7 -- 4.2 31 38 -- 7 7 PVB 3 PVB 8 PVB 3 4.2 32 40 32 8 8
PVB 3 PVB 9 PVB 3 4.2 32 40 32 8 9 PVB 6 PVB 4 -- 4.2 31 38 -- 7 10
PVB 6 PVB 5 -- 4.2 31 37 -- 6
Effects of salt concentrations on the adhesion of the gradient
region of interlayers of the present invention are shown in the
Table 4, where a single asterisk designates that laminates contain
two panes of symmetric glass sheet (2.1 mm) (each of the glass
sheets has equal thickness).
TABLE-US-00004 TABLE 4 Difference in total alkaline Total alkaline
titer titer between in interlayer clear and Pummel adhesion
Laminate Clear Gradient gradient Clear Gradient Adhesion delta No.*
region region regions region region (clear - gradient) 1 23 23 0
4.7 2.5 2.2 2 24 20 4 3.8 2.8 1 3 25 15 10 4.0 4.1 -0.1 4 25 8 17
4.0 5.1 -1.1
Effects of the incorporation of epoxy resin in the colored region
on the adhesion of the gradient region of interlayers of the
present invention are shown in the Table 5, where a single asterisk
indicates that laminates contain two panes of symmetric glass sheet
(2.1 mm), i.e., each of the glass sheets has equal thickness, a
double asterisk indicates that magnesium salt titer is the same in
all examples, and a triple asterisk indicates epoxy--1: DER 732 and
Epoxy--2: Heloxy 116.
TABLE-US-00005 TABLE 5 Total alkaline Phr of Epoxy-1 Phr of Epoxy-2
titer in both in Interlayer*** interlayer*** Pummel adhesion
Laminate clear and clear gradient clear gradient clear gradient
Adhesion No.* gradient** region region region region region region
delta (clear - gradient) 1 12 -- -- 0 0 6.6 3.6 3 2 12 -- -- 0 2
6.8 6.5 0.3 3 20 0 0 -- -- 5 3 2 4 20 0 2 -- -- 4.7 4.7 0 5 17 0 0
-- -- 4.5 3 1.5 6 17 0 2 -- -- 5 5 0
By virtue of the present invention, it is now possible to provide
multiple layer interlayers that have gradient regions having
colored regions and that reduce sound transmission and that are
easily handled and readily incorporated into multiple layer
constructs, such as laminated glass panels for windshields and
architectural windows.
While the invention has been described with reference to exemplary
embodiments, it will be understood by those skilled in the art that
various changes may be made and equivalents may be substituted for
elements thereof without departing from the scope of the invention.
In addition, many modifications may be made to adapt a particular
situation or material to the teachings of the invention without
departing from the essential scope thereof. Therefore, it is
intended that the invention not be limited to the particular
embodiments disclosed as the best mode contemplated for carrying
out this invention, but that the invention will include all
embodiments falling within the scope of the appended claims.
It will further be understood that any of the ranges, values, or
characteristics given for any single component of the present
invention can be used interchangeably with any ranges, values, or
characteristics given for any of the other components of the
invention, where compatible, to form an embodiment having defined
values for each of the components, as given herein throughout. For
example, a polymer sheet can be formed comprising residual acetate
content in any of the ranges given in addition to any of the ranges
given for plasticizer, where appropriate, to form many permutations
that are within the scope of the present invention but that would
be cumbersome to list.
Any FIGURE reference numbers given within the abstract or any
claims are for illustrative purposes only and should not be
construed to limit the claimed invention to any one particular
embodiment shown in any FIGURE.
Figures are not drawn to scale unless otherwise indicated.
Each reference, including journal articles, patents, applications,
and books, referred to herein is hereby incorporated by reference
in its entirety.
* * * * *